The present invention relates generally to human immunodeficiency virus and more specifically to a mutant form of an HIV co-receptor, CCR2, and its association with AIDS progression.
Chemokines are a subgroup of immune factors that have been shown to mediate chemotactic and other pro-inflammatory phenomena (see Schall, 1991, Cytokine 3:165). The chemokines are generally short peptides. The family of chemokines or intercines, is subdivided into two distinct subfamilies, the C-X-C and Cxe2x80x94C chemokines, according to the arrangement of the first two cysteines in their primary sequence. The members of the Cxe2x80x94C chemokine subfamily have remarkable similarities in their structural organization and biochemical properties. These homologies are consistent with the analogies observed in their biological effects, both in vitro and in vivo. For example, RANTES, MIP-1xcex1, and MIP-1xcex2 are all potent inducers of T-cell and mononuclear phagocyte chemotaxis, and exert diverse effects on eosinophilic and basophilic polymorphonuclear leukocytes (see Schall, op. cit.)
The Cxe2x80x94C chemokine receptors belong to the G-protein coupled receptor superfamily 20 (see Murphy, 1994, Ann. Rev. Immunol. 12:593; Neote, 1993, Cell 72:415; Raport, 1996, J. Leukocyte Biol. 59:18). The Cxe2x80x94C chemokine receptors consist of 7 transmembrane domains, and typically contain no introns (e.g. Federsppiel et al., 1993, Genomics 16: 707; Nomura et al., Int. Immunol. 5:1239)
It has recently been shown that the chemokines RANTES, MIP-1xcex1, and MIP-1xcex2, act as natural suppressors of HIV-1 infection (see Cocchi et al., 1995, Science 270:1811; Baier et al., 1995, Nature 378:563). Several groups have shown that the Cxe2x80x94C receptor CCR5, which acts as the principal cellular receptor for RANTES, NIIP-1xcex1, and MIP-1xcex2 is an efficient co-receptor for macrophage trophic isolates of HIV-1 (e.g. Combadiere et al., 1996, J. Leukocyte Biology 60:3362). The closely related CCR2 molecule can also act as a co-receptor for some HIV-1 strains (see Doranz et al, 1996, Cell 85:1149; Deng et al., 1996, Nature 381:661). CCR2 serves as a competent co-receptor for at least one dual trophic HIV-1 strain, but not for other M-tropic strains that utilize CCR5 (Choe, et al., 1996, Cell 85: 10 1135; Doranz et al., 1996, Cell 85:1149). The importance of such dual-tropic strains is unclear. Recently, a novel CCR5 deletion mutant, termed CCR5-xcex9432 has been reported (Dean et al., Science 273: 1856-62; Samson et al., Nature 382: 722-725; Liu et al., 1996, Cell 86: 367-77). Cells from homozygous CCR5-A32 individuals are highly resistant to infections. Individuals homozygous for the CCR5-A32 gene appear to be resistant to HIV infection in spite of multiple exposures. Individuals heterozygous for CCR5-xcex9432 and the normal CCR5-+ allele postponed the onset of AIDS.
The CCR5 deletion mutants, plus several HLA associations that influence exposure outcome (Kaslow et al., 1996, Nature Med. 2:405; Haynes et al., 1996, Science 271-324; Detels et al., 1996, AIDS 10:102) implicate a genetic explanation for epidemiologic heterogeneity of infection and progression, but they account for only a small proportion of exposed uninfected individuals or xe2x80x9clong term survivorsxe2x80x9d that continue to resist AIDS-defining illness 10-15 years after HIV-1 infection. For example, nearly 80% of exposed uninfected individuals are not CCR5-xcex9432 homozygotes and over 60% of long-term survivors are homozygous CCR5+/+.
The present invention is based on the discovery of a variant of the CCR2 chemokine receptor which is associated with reduced progression to AIDS in HIV-infected subjects. The invention provides nucleic acid compositions which encode the CCR2 variant chemokine receptor gene, herein referred to as CCR2-64I. Vectors and host cells for expressing CCR2-64I are also provided. The nucleic acid compositions find use in diagnostic methods for the identification of individuals having a CCR2-64I allele in order to determine the likelihood that HIV-infected individuals will progress to rapid disease progression; in diagnostic methods for the identification of individuals carrying the CCR2-64I allele in order to determine treatment regimens for patients infected with HIV; for production of the encoded variant protein for antibody production; and in anti-viral therapy. A method for treating and preventing diseases which involves the inflammatory response, such as asthma, arthritis, Crohn""s disease, lupus, Grave""s disease, and pulmonary disease associated with cystic fibrosis, is also provided.
One aspect of the invention features isolated substantially purified CCR2-64I polypeptide and nucleic acid molecules that encode CCR2-64I. In a particular aspect, the nucleic acid molecule is the nucleotide sequence of SEQ ID NO:19. In addition, the invention features nucleic acid sequences that hybridize under stringent conditions to SEQ ID NO:19.
The invention additionally features nucleic acid sequences encoding CCR2-64I polypeptides, oligonucleotides, fragments, portions or antisense molecules thereof, and expression vectors and host cells comprising polynucleotides that encode CCR2-64I. The present invention also relates to antibodies which bind specifically to a CCR2-64I polypeptide as opposed to wild-type CCR2; pharmaceutical compositions comprising substantially purified CCR2-64I, fragments thereof, or antagonists of CCR2-64I, in conjunction with a suitable pharmaceutical carrier, and methods for producing CCR2-64I.
It is a further object of the present invention to provide a therapeutic modality consisting of transplantation into a patient suffering from a disease characterized by HIV-1 infection, of bone marrow or umbilical cord stem cells from compatible individuals that carry the CCR2-64I allele, or transplantation of treated cells from the patient (i.e., autologous transplant).
Another object of the present invention is to provide diagnostic methods for the identification of individuals carrying the CCR2-64I allele based on the amplification of the CCR2 sequence, or hybridization to the sequence, to reflect the presence or absence of the CCR2-64I allele.
Another object of the invention is to provide a diagnostic kit for determining the CCR2 allelic profile of an individual, comprising amplification primers, hybridization probes or antibodies which recognize wild-type CCR2 and amplification primers, hybridization probes, or antibodies which recognize CCR2-64I.
A further object of the invention is to provide a method for treating or preventing in a subject having or at risk of having, a disease characterized by HIV infection, comprising administering to a patient bone marrow cells, CD34+ cells, umbilical cord cells, or CD4+ cells from an individual homozygous for CCR2-64I.
An object of the invention is to provide antibodies that bind CCR2-64I specifically, such that the antibody is suitable for use in diagnosing or treating a disease characterized by HIV infection or another inflammatory response.
In fulfilling these and other objects, there has been provided, in accordance with one aspect of the invention, a method of treating or preventing a disease characterized by HIV infection or an inflammatory response, comprising administering to a patient an agent to inactivate the CCR2 receptor. In a preferred embodiment the agent is a Cxe2x80x94C chemokine analog, an antibody, an oligonucleotide antisense to CCR2 mRNA, or a ribozyme. In another preferred embodiment, the agent is administered ex vivo or is administered directly to the patient.